The investigator has designed a pilot (prior to a full-scale) study to determine whether the naloxone stimulation test will provide a simple, safe, and reliable alternative to the insulin tolerance test and various other screening tests in the evaluation of patients with suspected central adrenocortical (CAC) insufficiency. The study will establish the magnitude of the plasma ACTH and cortisol responses to naloxone that will permit the best combination of sensitivity and specificity for the detection of CAC insufficiency. Twenty-three of the 30 subjects planned for this pilot study have been enrolled.